Gas turbine system



Jan. 22, 1935. A. LYSHOLM GAS TURBINE SYSTEM Filed March 19, 1951 FUfLf5 57 26 T i INVENTOR WW w ATTORNEY,

was Jan. 22, 1935 4 i I I 1,988,456

UNITED STA'THES'PATENT .IOfl-FlCE GAS TURBINE SYSTEM an Lyaholm,Stockholm, Sweden, alsignor' to Aktiswegbolaget Milo, a joint-stockcompany of en I Application March 19, 1931, Serial No. 523,767 InGermany March 24, 1930 BGlaims- (01.6042) The present invention relatesto gas turbine sys- In accordance with the present invention, the temsand has particular reference to the producadvantages to be derived fromburning fuel to tion of gaseous motive fluid comprising gases of producea motive fluid having relatively little excombustion for use intheturbines of such systems. cess air are obtained while at the same timethe 5 Since the amount of energy available in the modifllcultlesheretofore encountered, when motive 5 tive fluid is dependent upon thequantity and temfluid of such character has been provided in acperatureof the gases and also upon the speciflc cordance with prior suggestions,are eliminated,

heat thereof, the amount, of energy may be inas will hereinafter be morefully explained. creased by increasing the gas temperature through Inorder to be suitable for use in gas turbines,

the burning of an increased amount of fuel, but the motive fluid shouldbe substantially soot free, 10 this method of increasing the energy islimited by since it is obvious that any substantial amount of themaximum temperature of motive fluid usable 'soot or free carbon in thefluid will form deposits in the turbines. In order to increase to thedesired in the conduits and turbine blading and eventuvalue the energyavailable it is therefore necessary ally materially reduce the,efliciency and capacity in some instances to compress the combustionsupof the system. Practice has shown'that for fuels is porting medium toa relatively high pressure, and having soot forming characteristics itis usually also, in some cases, it is highly desirable to obtainnecessary to provide an excess of air of at least the desired results byincreasing the speciflc heat about30% in order to obtain perfectcombustion. of the gaseous motive fluid by the injection of As haspreviously been explained, the provision water, which at the temperatureof the gases is of compressor capacitysufllcient to supply such 20converted into steam. quantity of excess air when the system is operat-The most economically advantageous way of seing at maximum capacityinvolves undesirable curing the required energy in the motive fluiddecosts and this I .avoid by forming motive fluid pends, however, uponthe character of the load for with two different kinds of fuel,'one ofwhich has which the system is intended. If the system is non-sootingcharacteristics, when the. load on the intendedfor continuous base loadoperation, comsystem is of relatively high value. By doing this pressorapparatus producing the necessary com-' I am able to utilize to the bestadvantage subpressed combustion supporting gaseous medium stantially allof the combustion supporting memaybe employed which compressescomparatively dium delivered from the compressor apparatus.- largevolumes of such medium at relatively low I also may make use of waterinjection in pro- 30 pressure, with substantial excess air in themoducing the motive fluid. tive fluid as finally produced, such excessair serv- The invention is applicable in its use to a wide ing toprevent the production of excessive temvariety of specific arrangementsof gas turbine perature of the motive fluid. Such apparatus, systems orplants, and for purposes of illustration however, involves the use ofcompressor and other only and in order that the nature of the inventionapparatus of such size and cost that the capital and the manner of itsuse may be readily under-' charges render the arrangement economicallyun-' stood, I have illustrated in the accompanying attractive for use insystems intended for carrying more or less diagrammatic drawing onearrangepeak loads, either alone .and therefore usually ment of gasturbineapparatus embodying the 40 involving only periodic operation ofthe system, invention. or superimposed on a base load and involving wideIn the drawing: f variations in the motive fluid energy required by Fig.1 is a more or less diagrammatic view the system. showing a gas turbinesystem suitable for varia- For systems intended to carry variable orpeak ble load operation and embodying the invention; loads, it mayfrequently be advantageous to seand cure the energy required to carryhigh values of Fig. 2 is a more or less diagrammatic sectional load byburning additional fuel in a compressed view on a larger scale of acombustion chamber medium the maximum quantity of which that isarrangement Sui a le for use n y m m y- 7 available is so limited by thesize of the compresing the invention. 7 5 sor apparatus that relativelylittle if any excess Referring to Fig, 1, reference characters 1, 2, 5air is present in the motive fluid when such addi- 3 and 4 designatefour turbines or turbine sections tional fuel is burned. When this isdone, the driving a common shaft 4". Reference character system cancarry relatively high peak loads with- 5. denotes a compressor driven byshaft 4 and 6 out there being required compressor apparatus ofdesignates an electric generator also driven by this relatively largecapacity. shaft. The net useful power delivered by the system isobtained from generator 8 in the form of electrical energy.

In the compressor 5 the combustion supporting medium, in this case air,is compressed to the desired pressure. Air flows to the compressorthrough inlet conduit '7 and after being compressed is led throughconduit 8 to the combustion chamber or heating apparatus designated at9. Fuel is admitted to the combustion chamber, in a manner to behereinafter explained, through conduits 10 and 11 and water may besupplied through conduit 12. Control of the fuel and water may beeffected in any suitable manner, as by valves indicated at 43, 44 and45. The motive fluid produced by combustion of fuel in chamber 9 ledthrough conduit 13 and branch 14 to the inlet of the high pressureturbine 1, and the motive fluid exhausted from this turbine at reducedtemperature and pressure is led through conduit-15 to the intermediatepressure turbine 2 for further expansion therein. From turbine 2 thepartially expanded motive fluid is conducted through conduit 16 to thesecond intermediate pressure turbine 3 and from this latter turbine themotive fluid flows through conduit 1'7 to the low pressure turbine 4 forflnal expansion in the system. Exhaust is through conduit 18.

The inlet'of turbine 2 is connected to conduit 13 by means of branchconduit 19 having the valve 20 therein. At an intermediate pressure zonein the compressor 5 a conduit 21, preferably valved as at 53, serves towithdraw air at suitable intermediate pressure. Conduit 21 is connectedby means of branch conduits 22, 26 and 31, having therein valves 54, 55and 56 respectively, to separate combustion chamber or heating apparatusdesignated generally at 23, 2'7 and 30. Chamber 23 is connected toconduit 15 by branch 25; 27 is connected to conduit 16 by branch 29; and30 is connected to conduit 1'7 by branch 33. Fuel is supplied tochambers 23, 2'7 and 30 through branch fuel conduits 24, 28 and 32respectively in which are located the respective control valves 5'7, 58and-59.

Fig. 2 shows on a larger scale an advantageous form of the combustionchamber apparatus 9. In this form two spaced shells or casings 36 and3'7 provide a jacket space to which water flows from thesupply conduit12. The fuel supply conduit extends inwardly at 10 to a nozzle 10 and issurrounded by the pipe 38 which communicates with the jacket space andwhich terminates in a suitable nozzle 38 The extension 10" mayadvantageously contain a suitable spraying device 47. Conduit 11 isextended as at 11 to a nozzle 11 and is advantageously provided with aspraying device 48. Pipe is extended inwardly from jacket space 35 toanozzle 40 surrounding nozzle 11 and is preferably controlled by asuitable valve 46. A third water pipe 39 is advantageously provided,having nozzle 39 and spraying device 49.

Let it be assumed that the foregoing briefly described system isoperated as a variable load plant, which may be either a base load plantadapted to carry peak loads or as a peak load plant adapted to carrypeak loads of varying values. The operation at various loads is asfollows:

When the load on the plant is low fuel is supplied through conduit 10,this fuel being of the kind having soot forming characteristics, suchfor example as ordinary fuel oil or like cheap fuel. Since the amount offuel'req uired is relatively low the amount of compressed air availableis such that the fuel is burned in the presence of considerable excessair and the complete combustion thus obtainable prevents the formationof soot. The excess air also serves to prevent formation of a motivefluid of too high a temperature to be usable in the turbines.

If the load increases, thus necessitating the introduction of more fuel,the amount of excess air decreases and when it decreases to a certainvalue, the tendency to form soot arises. Also, the temperature of themotive fluid increases. When this condition occurs, water may beinjected, since the action of water in such instances tends to reduce orprevent the formation of soot. The injection of water also serves tomaintain the temperature below the permissible maximum and while thetemperature is reduced owing to the water injection, the total energy ofthe motive fluid remains the same, since the volume and specific heatthereof are increased'by the steam formed as a result of the injectionof the water.

If the load increases to a value beyond that at which the soothing fuelcan be burned, even in the presence of water, without formation of soot,a fuel having non-sooting characteristics, such for example as alcohol,is supplied through conduit 11 to be burned with such excess oxygen asis available, thus making it possible to impart the greatest amount ofheat energy to the compressed air. The alcohol may be incompletelyburned, that is to say a relatively large amount of carbon monoxide maybe formed, thus reducing to some extent the combustion efiiciency, butfor the use intended the obtaining of maximum combustion efflciency isnot the controlling factor.

In order to utilize the motive fluid most effectively at the higherloads some of it may be admitted directly to the turbine 2 by openingvalve 20. V

For still higher loads the additional energy required may he obtained byreheating between turbines or turbine sections. Since before this may benecessary, substantially all of the available excess oxygen in the airsupplied to the combustion chamber 9 is ordinarily'used to burn thenon-sooting fuel, additional air must be supplied for combustion withthe fuel used for reheating. For this purpose the air at intermediatepressure is supplied from conduit 21 in suitably regulated amounts toone or more of the reheating combustion chambers 23, 2'7 and 30(depending upon how many times the motive fluid is reheated) andnon-sooting fuel is supplied through branches 24, 28 and 32 to suchreheating chambers as are used. By employing non-sootlng fuel forreheating, excess air is not required and while the temperature existingin the reheating chambers may reach very high values, the mixing of thefluid discharged therefrom with the cooler motive fluid exhausted fromthe higher pressure turbines provides for a reheated motive fluid ofusable temperature.

While various specific forms of heating and reheating apparatus may beemployed, I flnd it desirable when water injection is used to employ ajacketed combustion chamber of thekind illustrated and to utilize meanssuch as are shown at 4'7, 48 and 49 for effecting suitable spraying ofthe water and fuel.

From the foregoing description it will be evident that the invention isapplicable to a gas turbine system capable of carrying widely differingvalues of load and it will be equally apparent that the invention isapplicable to a wide variety of systems which may differ materially intheir arrangement from the arrangement herein described by way ofexample. It will also be understood that certain features may be usedwithin the scope of the invention to the exclusion -of others.

What I claim is:-

1. In a gas turbine system having turbine driven compressing means, apower output turbine and a combustion chamber, the method of operationwhich comprises supplying to the combustion chamber a combustionsupporting gaseous medium compressed in said compressing means,supplying to the combustion chamber a fuel having soot formingcharacteristics, burning said fuel in the presence of a substantialexcess of said medium to effect combustion substantially withoutformation of soot, introducing a second fuel adapted to burn withoutproducing soot when burned in the presence of insufficient oxygen tosupport complete combustion thereof, and buming said second fuel in theexcess of said'medium remaining after combustion of the first mentionedfuel, whereby to produce a substantially soot free motive fluidcomprising gases of combustion and utilizing said motive fluid as aturbine driving medium.

2. In a gas turbine system having turbine driven compressing means, apower output turbine and a combustion chamber, the method of operationwhich comprises supplyin to the combustion chamber a combustionsupporting gaseous medium compressed in said compressing means,supplying to the combustion chamber a fuelhaving soot formingcharacteristics, burning said fuel in the presence of a substantialexcess of said medium to efiect combustion substantially withoutformation of, soot, introducing a second fuel adapted to burn withoutproducing soot when burned in the presence of insuflicient ongen tocharacteristics and thereafter consuming sub- 7 stantially all of theremaining portion of said constituent by burning therewith a fuel havingnon-soot forming characteristics.

4. The improved method of producing a heated and substantially soot freegaseous motive fluid comprising gases of combustion which consists ininitially consuming a portion of the combustion supporting constituentof a gaseous medium by burning therewith a fuel having soot formingcharacteristics and thereafter consuming substantially all of theremaining portion of said constituent by burning therewith a fuel havingnon-soot forming characteristics in the presence of water.

5. In a gas turbine system having turbine driven compressing means, apower output turbine and a combustion chamber, the method of operationat different loads which comprises supplying a combustion supportinggaseous medium compressed in said compressing means to said combustionchamber and at light loads burning a sooting fuel therein in thepresence of an excess of said medium, at heavier loads burning anon-sooting fuel therein without substantial excess of said medium, toproduce a motive'fluid for said turbine and expanding said fluidserially in different turbine sections, and at still heavier loadsreheating said fluid between said sections.

6. In a gas turbine system havingturbine drlven compressing means, apoweroutput turbine and a combustion chamber, the method of opera-' tionwhich comprises supplying to the. combustion chamber a combustionsupporting gaseous medium compressed in said compressing means,supplying to the combustion chamber a fuel having soot formingcharacteristics, burning said fuel in the presence of a substantialexcess of said medium to effect combustion substantially withoutformation of soot, introducing a second fuel adapted to burn withoutproducing soot when burned in the presence of insuflicient oxygen tosupport complete combustion thereof, burning said second fuel in theexcess of said medium remaining after combustion of the first mentionedfuel, whereby to produce a substantially soot-free motive fluidcomprising gases of combustion, utilizing said motive fluid as a turbinedriving medium and reheating said motive fluid at an intermediatepressure stage by supplying thereto an additional quantity of saidsecond fuel and an additional quantity of said combustion supportinggaseous medium, wherebyto produce a reheated substantially soot-freemotive fluid comprising gases of combustion for expansion in a pressurestage below said intermediate pressure stage.

ALF LYSHOLM.

